P-51B

My Feedback: (5)

I am trying to decide between a Roto engine and an Evolution (MVVS/H9) engine to put on my Great Planes PT-17 ARF. I was leaning towards the Roto since the rear carb would provide less interferance with the fake radial engine, but either configuration will work.

I am curious about a performance and reliability comparison between the two from those who have experience with them. Any input on the pros and cons of each is appreciated.

Cheers!

Tired Old Man

My Feedback: (1)

Consistently tried using 6 Roto 25's for awhile sometime back. Wouldn't do it again.

P-51B

My Feedback: (5)

Thanks Silver.

It looks unanimous so far. I am kind of surprised since I hadn't heard anything bad about the Roto line befor now.

Marcol

Perhaps 6 Roto's were all ok and it was operator error.

I have the Roto 50 twin and it is just a great engine. We also have 3 other club members with the 35 single and they are very happy with their Roto's also.

So I'm afraid I take your advice with a large pinch of salt

dhooks

My Feedback: (24)

Silversurfer runs more engines in 6 mo then most of us do in a lifetime, if he says they dont run you may want to take it with a grain of salt.

Marcol

It don't mean he runs them right though. I'm not saying it's impossible but it seems hard to believe that 6 were bad.

I can only speak as I find and I and other members of our club find them a good, reliable , value for money engine.

dhooks

My Feedback: (24)

Yea they were run right. If he couldnt get an engine to run right he would be out of a job. He gets hundreds an hundreds of hours on engines in a very short period of time.

rmh

I did a few ROTOS- 35 and 25 -
just like any Walbro equipped engine - if there is a starting or running problem -it is likely the carb .
The Rotos I setup for others and myself, started and run very well . -one had a weepy casting -on front of case - made a small oil spot - other than that- a very well made engine .
for the best of the entire 25/26cc engines tho -my favorite is the 26 evolution/MVVS
it is light-and compact -the carb is not placed on engine side-so a very compact , smooth and powerful setup -on pipes, the Roto was almost as strong . we ran same fuel/ optomized the pipes etc., and compared overall setup against the EVOLUTION -
The new light ZDZ40F3A is 2.5 lbs -same weight as the ROTO 25.also it's new ignition setup makes this the smoothest running single I have ever run- It was developed for th elight weight F3A Pattern models which must weigh no more than 11 lbs all up- so it had to be very smooth at all stages of power. The only node -and it can still be felt but we can't see the shake -is at 3300rpm it is very small and is gone at either 3200 or 3400 . I checked this wuith the direct reading ZDZ tach. -on a wide variety of propellers 22x12 to 20x10.
I mention it because being a rear intake and exhaust -it will fit in cowls, narrower than any of the 25-26cc engines--with ehaust and intake completely enclosed. and weight is similat to these engines
If I ever did another scale P51 etc., this is what I would use for a totally hidden engine .

Tired Old Man

My Feedback: (1)

I'm not going to go into the background and discoveries, but let's say that about 10 people worked with those engines, and they all knew what they were doing quite well. Of the six engines, three are on the bottom of the ocean due to in flight failures, and another is there by choice. That was a bit less than two years ago. They've had some time to improve, and hopefully they have. Marcol can buy a few more and continue the testing process.

If you can't believe a quantity of 6, I don't think you could comprehend getting shipped several hundred engines with the piston ring pin in the wrong location. How about loose and poorly fit bearings in large numbers of engines? What about a 95% ignition failure rate? Better still, how about new servos that go up in smoke as soon as they are plugged into a cycler after coming out of the box? No manufacturers to be provided, period.

Then again, since I must be new at this stuff.....

Rcpilot

My Feedback: (78)

I think that about settles it.

Thread closed.